The U.S. Food and Drug Administration on Nov. 9 approved Sunharbo (asundexian), a once-daily pill from Bayer that is the first drug in a new class of blood thinners called factor XIa inhibitors. It is approved to lower the risk of another stroke in adults who recently had a mild-to-moderate ischemic stroke not caused by a clot from the heart, or a high-risk transient ischemic attack (TIA), often called a “mini-stroke,” the agency said.
Sunharbo is taken together with standard antiplatelet therapy, such as aspirin or clopidogrel. In the large trial that led to approval, adding it cut ischemic strokes by 26% compared with a placebo, without a significant overall increase in major bleeding.
“Stroke is a leading cause of disability and death in the United States, and survivors are at risk of having another stroke,” said Dr. Hylton V. Joffe, director of the FDA’s Office of Cardiology, Hematology, Endocrinology, and Nephrology. “Today’s approval represents a meaningful advance for patients and health care providers seeking a new option for secondary stroke prevention.”
What did the OCEANIC-STROKE trial show?
The phase 3 OCEANIC-STROKE study enrolled 12,327 adults at 702 centers in 37 countries. Participants had a recent non-cardioembolic ischemic stroke or a high-risk TIA and were randomly assigned within 72 hours of symptom onset to asundexian 50 mg once daily or a placebo, on top of antiplatelet therapy, according to results published in the New England Journal of Medicine.
Over a median treatment period of 14.2 months, ischemic stroke occurred in 6.2% of people taking asundexian and 8.4% of those taking a placebo, according to a summary of the published results. A combined measure of cardiovascular death, heart attack or stroke fell from 11.1% to 9.2%.
One result was less clear. The drug did not significantly reduce ischemic strokes in the first 90 days after the initial event (3.0% vs. 3.5%).
How is Sunharbo different from other blood thinners?
Factor XIa is a clotting protein that plays only a minor role in sealing injured blood vessels but helps clots grow larger and harder to break down. Blocking it is meant to prevent harmful clots while preserving more of the body’s ability to stop bleeding, a hazard with many existing blood thinners, BioPharma Dive reported.
Sunharbo is approved only for this group of stroke and TIA patients. It is not approved to prevent stroke in people with atrial fibrillation, the FDA said. An earlier Bayer trial in atrial fibrillation was stopped early after asundexian proved less effective than apixaban (Eliquis), according to results published in NEJM in 2025.
What are the bleeding risks and side effects?
Overall rates of major bleeding were similar in the two groups: 1.9% on asundexian and 1.7% on placebo in the published trial. But the FDA said major bleeding was higher with Sunharbo in patients older than 75 and during the first 90 days of treatment. Gastrointestinal bleeding was more common with the drug, and diarrhea was the most frequently reported side effect.
The FDA said Sunharbo is not recommended for people with moderate or severe liver impairment or for those taking certain medicines, such as carbamazepine, that may weaken it. It should be paused at least 24 hours before elective surgery and after clot-busting stroke treatment.
Who could benefit, and what will it cost?
More than 795,000 people in the United States have a stroke each year, and about 185,000 of them, nearly 1 in 4, have had a stroke before, according to the Centers for Disease Control and Prevention. About 87% of strokes are ischemic, meaning blood flow to the brain is blocked.
A 30-day supply of Sunharbo will carry a list price of $748.50, a Bayer spokesperson told BioPharma Dive. What patients pay will depend on their insurance or Medicare drug plan, and coverage decisions are not yet known. Bayer said it has set up a patient support program.
What should stroke survivors do now?
Anyone who has had a recent stroke or TIA should not start, stop or switch blood thinners on their own. Patients can ask their neurologist or primary care doctor whether Sunharbo fits their type of stroke, how it would work with their current antiplatelet medicine, and how their age, liver health and other drugs affect the bleeding risk.
It also helps to know the warning signs of a new stroke, including sudden numbness or weakness on one side of the body, confusion, trouble speaking or seeing, and a sudden severe headache. The CDC advises calling 911 right away. For more on recent heart and stroke research, see HNC’s coverage of two closely watched heart drug trials.
Key Takeaways
- The FDA approved Bayer’s Sunharbo (asundexian) on Nov. 9, the first factor XIa inhibitor blood thinner.
- It is approved, with antiplatelet therapy, for adults after a recent mild-to-moderate non-cardioembolic ischemic stroke or a high-risk TIA.
- In a 12,327-person trial, it cut ischemic strokes by 26% compared with placebo (6.2% vs. 8.4%).
- Overall major bleeding was similar, but higher in people over 75 and in the first 90 days of treatment.
- It is not approved for stroke prevention in atrial fibrillation. The list price is $748.50 for 30 days.
Frequently Asked Questions
What is Sunharbo?
Sunharbo is the brand name for asundexian, a once-daily 50 mg pill made by Bayer. It is the first FDA-approved factor XIa inhibitor, a new type of blood thinner.
Who is Sunharbo approved for?
Adults who recently had a mild-to-moderate ischemic stroke not caused by a clot from the heart, or a high-risk transient ischemic attack. It is taken with antiplatelet therapy.
Can people with atrial fibrillation take Sunharbo to prevent stroke?
No. The FDA said Sunharbo is not approved for stroke prevention in patients with atrial fibrillation.
Does Sunharbo raise bleeding risk?
In the main trial, overall major bleeding was similar to placebo. The FDA said bleeding was higher in patients older than 75 and in the first 90 days, and gastrointestinal bleeding was more common.
How much does Sunharbo cost?
Bayer set a list price of $748.50 for a 30-day supply. Out-of-pocket costs will depend on each person’s insurance or Medicare drug plan.
Sources: FDA news release (Nov. 9, 2026); New England Journal of Medicine (Sharma et al., OCEANIC-STROKE, 2026); Practical Neurology summary of the NEJM results; BioPharma Dive (Nov. 9, 2026); CDC stroke facts; NEJM OCEANIC-AF results (2025).
Photo: A U.S. Navy hospital corpsman working as a pharmacy technician separates pills into bottles. U.S. Navy photo by Petty Officer 2nd Class Jesus Aguiar, public domain, via Wikimedia Commons. The photo is illustrative and does not show Sunharbo.
